Archived

Avalanche Forecast

Feb 17th, 2018–Feb 18th, 2018

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Sea To Sky.

Fresh storm slabs will be reactive, especially in wind-affected terrain. Use extra caution around steep unsupported terrain features.

Confidence

Moderate -

Weather Forecast

SUNDAY: Gradual clearing and cooling as Arctic air pushes into the region, moderate to strong northeast wind and alpine high temperatures around -15 C.MONDAY: Sunny, moderate northeast wind, alpine high temperatures around -14 C.TUESDAY: Mostly sunny, light wind, alpine high temperatures around -12 C.

Avalanche Summary

Preliminary reports from Saturday indicate storm slabs were reactive to skier and explosive triggers, producing mostly small slabs (size 1) and one larger slab (size 2) in lee terrain.Several large cornices collapses were reported last week. One resulted in a fatal accident in the Callaghan area on Saturday. A snowmobiler was parked 7-10 m back from the edge of a corniced ridge when a large chuck broke off and took the rider down the slope. See here for a full report. Cornices grew larger with Saturday's storm.

Snowpack Summary

25-40 cm of fresh snow sits above variable interfaces including hard wind-affected snow in exposed terrain, a hard crust below 1900 m, and a sun crust on south-facing alpine slopes. Deeper deposits of storm snow exist in lee and cross-loaded alpine terrain. The mid-January crust is now buried beneath 150-200 cm of settled snow, but a heavy trigger such as a cornice fall could potentially wake up this layer. The lower snowpack is generally strong and well-settled.

Avalanche Problems

Storm Slabs

25-40 cm of fresh snow from Saturday's storm has formed reactive storm slabs, especially in wind-affected terrain at higher elevations.

Use conservative route selection, choose moderate angled and supported terrain with low consequence.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Use caution on open slopes and convex rolls

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 2

Cornices

Large, looming cornices have formed along ridgelines. They need to be given an extra wide berth from above and below. A large cornice collapse in the wrong location may have the ability to trigger a large avalanche on the slope below.

Stiff cornices can easily pull back into flat terrain at ridgetop if they fail.Falling cornices may trigger large avalanches on the slopes below.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 1 - 2.5